The California Highway Patrol says it was around 5:30 pm when a semi-truck was headed east on Grangeville while a woman behind the wheel of the ATV entered the road.
"Attempted to make a u-turn across the roadway and didn't look both ways," says CHP Officer Gary Giles.
The driver of the semi-truck didn't want to speak to Action News on camera, but he tells us the woman driving the ATV appeared to be checking the mail.
Before he knew it, she was making a u-turn to get back across the road.
CHP says the semi swerved to the left to try and avoid the woman in the ATV but the vehicles still collided.
"Could not avoid the vehicle in the short amount of distance that it happened," Giles said.
Investigators say speed or alcohol were not factors in the crash.
Giles urges drivers to take extra caution on rural two-lane roads where vehicles are traveling fast and there's not a designated place to make a u-turn.
"Stop before entering the roadway," he said. "Look both ways. Stop to make sure that there's no other traffic coming before attempting to cross the road."
The woman was taken in an ambulance to Adventist Health in Hanford. At this time, she's still in critical condition.